THE FAUNAS
Reading edition
We have mentioned elsewhere that three different mammalian faunas occur in Washington. These may be described as follows.
1. The Great Basin Fauna. This fauna is best typified by such genera as Perognathus and Dipodomys. Species that, at least in Washington, are confined to this fauna are:
Sorex merriami Tamias minimus
Myotis thysanodes Perognathus parvus
Myotis subulatus Dipodomys ordii
Pipistrellus hesperus Onychomys leucogaster
Antrozous pallidus Reithrodontomys megalotis
Taxidea taxus Lagurus curtatus
Marmota flaviventris Lepus californicus
Citellus townsendii Sylvilagus nuttallii
Citellus washingtoni Sylvilagus idahoensis
The break between the Great Basin Fauna and the other two faunas is extremely sharp, probably as a consequence of a sharp break in the flora.
2. The Pacific Coastal Fauna. The mammals of the humid coastal district range from the Fraser River, British Columbia, southward to the vicinity of Monterey Bay, California. In Washington typical genera are Aplodontia, Neurotrichus and Scapanus. The following species are typical of the Pacific Coastal Fauna in Washington:
Neurotrichus gibbsii Tamiasciurus douglasii
Scapanus townsendii Sciurus griseus
Sorex trowbridgii Clethrionomys californicus
Sorex bendirii Microtus townsendii
Marmota olympus Microtus oregoni
Tamias townsendii Aplodontia rufa
Some species which range outside this faunal area have strongly marked races confined to it. Glaucomys sabrinus oregonensis and Lepus americanus washingtonii are examples. The Pacific Coastal Fauna is a forest fauna. Like the Great Basin Fauna, it reaches its northern limit of distribution in Washington and is better represented farther south. Unlike the Great Basin Fauna, the break between the Pacific Coastal and the surrounding fauna is not sharp, because forests continue into the more boreal faunal areas to the north and east. There, some mingling of coastal and Rocky Mountain faunas occurs.
3. Rocky Mountain Fauna. If this fauna be thought of as including mammals of the Rocky Mountains of the United States, and also those of the subarctic faunal area to the east of these mountains in Canada, the species in Washington are as follows:
Sorex palustris Synaptomys borealis
Microsorex hoyi Phenacomys intermedius
Lynx canadensis Clethrionomys gapperi
Marmota caligata Microtus richardsoni
Citellus lateralis Ochotona princeps
Citellus columbianus Lepus americanus
Tamias amoenus Rangifer montanus
Tamiasciurus hudsonicus Oreamnos americanus
Glaucomys sabrinus
Of the three, the Great Basin Fauna is the most distinct. Only about twenty species which occur within the Great Basin Faunal Area, occur also outside of it in one or both of the two other faunal areas. Most of these twenty are subspecifically different in the Great Basin Faunal Area as contrasted with one or both of the other areas. Each of the other two areas has no less than 32 species that are not restricted to it.